Flexible liquid crystal cells and lenses

ABSTRACT

A flexible optical element adopting liquid crystals (LCs) as the materials for realizing electrically tunable optics is foldable. A method for manufacturing the flexible element includes patterned photo-polymerization. The LC optics can include a pair of LC layers with orthogonally aligned LC directors for polarizer-free properties, flexible polymeric alignment layers, flexible substrates, and a module for controlling the electric field. The lens power of the LC optics can be changed by controlling the distribution of electric field across the optical zone.

PRIORITY APPLICATION

This application is a divisional of U.S. patent application Ser. No.16/045,024, filed 25 Jul. 2018, which application claims the benefit ofU.S. Provisional Patent Application No. 62/544,543, filed 11 Aug. 2017,which applications are incorporated herein by reference.

BACKGROUND Field

The present invention relates to electroactive optics and lenses usingsuch optics and, in particular, to flexible liquid crystal cells andlenses.

Description of Related Art

As soft contact lenses are handled by contact lens wearers, they aresubject to deformation. In some cases, the lenses may be folded in halfover short folding radii, as small as 2 millimeters or so. Thus, thesoft contact lens should be flexible enough to endure this deformationwithout damage over reasonable useable lifetime. It is desirable alsothat the lens be elastic in the sense that it is capable of recoveringits size and shape and of retaining the optical properties of the lensafter recovering from the deformation. A number of polymers, includinghydrogel contact lenses and silicone hydrogel contact lenses, have beendeveloped with flexibility and elasticity in mind.

In electroactive lenses, the electroactive components, such as liquidcrystal cells, can be embedded in a lens body made of a flexible andelastic polymer. However, electroactive components can limit both theflexibility and the elasticity of the lens body as a whole.

It is desirable to provide a lens with electroactive components that isboth flexible and elastic.

SUMMARY

An elastic or flexible, electrically tunable liquid crystal lens isdescribed. The liquid crystal lens includes a cell with a cell gapthickness that is substantially retained after it has been folded andreturned to its original shape. Thus, the shape and optical propertiesof the liquid crystal lens can recover after folding.

Embodiments described include an electroactive cell comprising a liquidcrystal in a gap between polymeric alignment layers, with an array ofpolymer posts disposed in the gap between the alignment layers.

In examples described herein, one or more of the alignment layerscomprises a flexible polymeric material including embedded liquidcrystal moieties.

Some examples of an electrically tunable lens described herein comprisea first alignment layer and a second alignment layer; an array ofelastic polymer posts in a gap between the first alignment layer and thesecond alignment layer, posts in the array extending from the firstalignment layer to the second alignment layer; liquid crystal confinedin the gap between the first and second alignment layers around posts inthe array; and one or more electrodes arranged to induce an electricfield in the liquid crystal.

A polarization-independent example includes a third alignment layer anda second array of elastomer posts in a second gap between the secondalignment layer and the third alignment layer, posts in the second arrayextending from the second alignment layer to the third alignment layer.Also, liquid crystal is confined in the second gap around posts in thesecond array. The second alignment layer in the example can includeliquid crystal moieties having directors aligned orthogonal to anoptical path and parallel near a first surface adjacent to the firstmentioned gap, and directors aligned orthogonal to an optical path neara second surface adjacent to the second mentioned gap and orthogonal tothe directors near the first surface.

Methods for manufacturing flexible liquid crystal cells are described,including formation of polymer posts in liquid crystal layers byphoto-polymerization according to a pattern. In an embodiment describedherein, the method includes assembling a first flexible alignment layerand a second flexible alignment layer with a gap therebetween; formingflexible or elastic polymer posts extending across the gap between thefirst flexible alignment layer and the second flexible alignment layer;and providing liquid crystal material surrounding the posts in the gap.In embodiments described herein, the method includes providing acombination of a liquid crystal material and a polymer precursormaterial in the gap, and forming the elastic posts by inducing phaseseparation of the polymer precursor and liquid crystal, and polymerizingthe polymer precursor according to a pattern.

Various combinations and additions to the devices and methods aredescribed below.

Other aspects and advantages of the present invention can be seen onreview of the drawings, the detailed description and the claims, whichfollow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified illustration showing folding of a flexible lenswith an electroactive cell as described herein.

FIG. 2 illustrates a flexible liquid crystal electroactive cell having asingle liquid crystal layer.

FIGS. 3A, 3B, 3C and 3D illustrate alternative embodiments of apolarization-independent, flexible liquid crystal electroactive cellhaving two liquid crystal layers.

FIGS. 4(a), 4(b), 4(c), 4(d), 4(e) and 4(f) illustrate stages in amanufacturing process for a flexible electroactive cell.

FIG. 5 shows an example layout for a lithographic mask used in processeslike that of FIGS. 4(a), 4(b), 4(c), 4(d), 4(e) and 4(f).

FIGS. 6(a), 6(b), 6(c), 6(d), 6(e) and 6(f) illustrate stages in themanufacturing of a polymeric layer like that used in the structure ofFIGS. 2 and 3A, 3B, 3C, and 3D.

FIG. 7 illustrates an example of a curved, flexible liquid crystalelectroactive cell.

FIG. 8 illustrates an example of a curved, flexible liquid crystalelectroactive cell having two layers of liquid crystal.

FIG. 9 illustrates an example of a two-layer liquid crystal cell, havinghybrid alignment in the liquid crystal layers.

FIG. 10 illustrates an example of a two-layer liquid crystal cell,having hybrid alignment in the liquid crystal layers with an alternativeelectrode position.

FIG. 11 illustrates an example of a two-layer liquid crystal cell with acurved dielectric layer.

FIG. 12 illustrates another example of a two-layer liquid crystal cellwith a curved dielectric layer, with hybrid alignment in the liquidcrystal layers.

FIG. 13 illustrates an example of a two-layer liquid crystal cell, withlens power in liquid crystal polymeric films.

DETAILED DESCRIPTION

A detailed description of embodiments of the present invention isprovided with reference to the FIGS. 1-13 .

FIG. 1 illustrates a lens 10 having an electroactive cell 11 embeddedtherein. The lens 10 is flexible and can comprise a hydrogel material ora silicone hydrogel material for example. The electroactive cell 11includes electroactive material and at least one electronic componentthat is used to change the refractive power of the lens. As illustratedin FIG. 1 , the lens 10 can be folded when it is made of a flexiblematerial as it is handled by the user. For example, when the lens 10 isa contact lens, then the user may fold the lens when inserting andremoving it from the eye. When the lens is folded as illustrated in thelower portion of the Figure, the radius R of the fold can be very smallparticularly in region 12. For example, a lens can be folded on a foldradius on the order of 1 to 9 mm, or over a fold radius less than 10 mm.When the lens is folded, the electroactive cell 11 can be deformed.

In embodiments described herein, the electroactive cell is elastic inthe sense that it recovers its shape and its tunable or adjustableoptical characteristics when returned to its original shape, after it isfolded.

FIG. 2 illustrates a flexible single layer liquid crystal cell which iselastic in the sense described above. The liquid crystal cell includes aliquid crystal layer 25 disposed in a gap between an upper (first)polymeric layer 24 and a lower (second) polymeric layer 27, where thepolymeric layers 24, 27 comprise a flexible or elastic polymer mixedwith liquid crystal moieties configured to act as alignment layers forthe liquid crystal layer 25. The polymeric layers 24, 27 have liquidcrystal moieties having a vertical director in the central region of thelayers, and horizontal directors on the surfaces. In the upper polymericlayer 24 in this example, the directors near the surfaces are orthogonalto the z-axis 5, which can be the optical axis, and horizontal relativeto the major surface of the liquid crystal layer 25, extending into andout of the plane of the illustration. In the lower polymeric layer 27 inthis example, the directors on the opposing surfaces are horizontalrelative to the major surface of the liquid crystal layer 25, extendinginto and out of the plane of the illustration. The orientations of thedirectors in this example result in the alignment directions on theupper and lower surfaces of the liquid crystal layer 25 being parallelto one another.

In this example, the liquid crystal layer 25 has a uniform thickness Tbetween the polymeric layers 24, 27, at least across an effectiveaperture of the liquid crystal cell. For the purposes of thisdescription, a liquid crystal layer has a uniform thickness across aneffective aperture of a cell when a user of the cell perceives theoptical performance as falling within a range expected for a cell havinga nominally uniform thickness, as such a range can occur in a commercialmanufacturing setting subject to environmental, manufacturing andmaterial variances.

An array of posts (e.g. post 26) is disposed in the gap between thepolymeric layers 24, 27 inside the liquid crystal layer. The posts inthe array extend from the upper polymeric layer 24 to the lowerpolymeric layer 27, and tend to maintain the thickness T. The posts(e.g. 26) can comprise a polymer or polymeric material. Preferably theposts are elastic. Also, preferably, the polymeric layers comprise anelastic polymer or elastomer.

Liquid crystal material is confined in the gap between the first andsecond polymeric layers around the posts in the array of posts, and actsas the active element of the cell, changing the optical characteristicsof the cell in response to an applied electric field.

In this example, electrical components used to apply an electric fieldin the liquid crystal layer 25 are disposed in a dielectric polymer(including layers 20, 22, 29 in this example). The electrical componentsinclude a resistive layer 23, a circular hole patterned electrode layer21 over the upper polymeric layer 24, and transparent pad electrodelayer 28 below the lower polymeric layer 27. In this, and in otherembodiments described herein, the patterned electrode layer can havepatterns other than a circular hole in some embodiments, includingpixelated patterns, and ring-shaped patterns, for more complex controlof the shape of the electric field vectors in the liquid crystal layer.

In one representative embodiment, the substrate of the liquid crystalcell includes the dielectric layers 20, 22 comprisingpolydimethylsiloxane (PDMS) about 17 μm thick each. The dielectric layer29 likewise comprises PDMS about 17 μm thick or less. The patterned andpad electrode layers 21, 28 can comprise a flexible electrode materialabout 1 μm thick or less. The liquid crystal layer 25 can be about 30-40μm thick, such as about 34 μm thick. The upper and lower polymericlayers can be about 6 to 7 μm thick. In this example, the cell has atotal thickness of about 98 μm.

In a further embodiment, the substrate of the liquid crystal cellincludes the dielectric layers 20, 22 comprising PDMS, each dielectriclayer has a thickness from 15 μm to 20 μm. Similarly, the dielectriclayer 29 can comprise PDMS and have a thickness from 15 μm to 20 μm. Thepatterned and pad electrode layers 21, 28 can comprise a flexibleelectrode material having a thickness from 0.1 μm to 1 μm. The liquidcrystal layer 25 can be 25 μm to 45 μm thick. The upper and lowerpolymer layers can each have a thickness from 5 μm to 10 μm.

In a representative embodiment, the thickness T of the liquid crystallayer 25 is about 34 μm.

In some embodiments, the thickness T is a constant thickness throughoutthe optical zone of the liquid crystal layer 25, where the optical zoneis the effective aperture in which the tunable lens effect is utilized.

A uniform thickness for the cell in this example can be a thickness thatvaries by less than 1.2 microns from the center of the optic to the edgeof the effective aperture. In some embodiments, the variation ofthickness T within the effective aperture can be maintained within 0.5micron.

Embodiments of the liquid crystal cells described herein can maintainoptical properties after having been folded over a small radius, andreturned to the original shape. For example, in an embodiment comprisinga cell gap having an average original thickness T with the liquidcrystal layer before folding of about 10 μm, the average thickness T canreturn to within 10% of its original thickness, or to an averagethickness in the range of 9 to 11 μm after folding over a fold radius ofless than 10 mm. In other embodiments, the average thickness T canreturn to within 2% of its original thickness, or to an averagethickness in the range of 9.8 to 10.2 μm. The average thickness of thecell gap or the liquid crystal layer can be determined by measuring thethickness at multiple locations and adding those measurements togetherand dividing by the number of measurements. The measurements can betaken along a single diameter of the liquid crystal layer (if it has acircular shape), or they can be taken along random points around theliquid crystal layer.

Depending on the requirements of particular implementations, thematerials of the flexible dielectric layers 20, 22, 29 acting asubstrate for the liquid crystal layer can be chosen from a variety ofpolymers and elastomers and combinations thereof suitable forutilization in a lens, including PDMS-containing materials, PET(polyethylene terephthalate)-containing materials, and hydroxyethylmethacrylate (HEMA)-containing materials.

Depending on the requirements of particular implementations,representative materials usable for the patterned electrode layer 21 andfor the transparent pad electrode 28 can bepoly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS),indium tin oxide (ITO), indium zinc oxide (IZO), graphene, silvernanowires and copper metal mesh, and combinations of materials.

A function of resistive layer 23 is to help distribute the electricfield into the center of the effective aperture of the lens. Theresistive layer 23 has a relatively high resistance relative to theelectrodes, and can be referred to as a highly resistive layer. With theresistive layer 23, the operating voltage can be decreased in someexamples. The sheet resistance of a resistive layer can be around10⁶˜10⁸ ⋅/sq depending on the lens materials and specifications. Theresistive layer can be made by mixing PEDOT:PSS solution and PVA(Poly(vinyl alcohol)) solution. The sheet resistance can be controlledfor example by the weight ratio between two solutions.

Liquid crystals (LC) are optical anisotropic materials which have abirefringence property. Consider a linear-polarized light which isnormally incident to LC optics and the polarization direction and longaxis of LC molecules are in the same plane. The light experiences aneffective refractive index which is determined by the angle betweenpolarization-direction of light and the director of LC. In addition, theorientation of LC molecules can be controlled by external electricfields. Therefore, a non-uniform electric field on the LC layer withuniform thickness will cause spatial distribution of the orientation ofLC molecules. The spatial distribution of the orientation of LCmolecules will also form a spatial distribution of effective opticalpath. By appropriate design, the spatial distribution of effectiveoptical path can realize the lens effect with different lens powers.

LCs can be polarization dependent, which can cost at least 50% of lightefficiency when used in combination with a polarizer. To realizepolarization-independent LC optics, a pair of LC layers with identicalthickness and orthogonally aligned LC directors, as implemented in theexamples shown in FIGS. 3A to 3D, can be used. Using the pair of LClayers with orthogonal directors, two Eigen-polarizations of lightexperience the same phase shift, resulting in apolarization-independent, tunable lens.

FIGS. 3A-3D illustrate alternative embodiments of flexible, two-layerliquid crystal cells which are elastic in the sense described above.These alternative embodiments can be made using materials discussedabove with respect to FIG. 2 .

In FIG. 3A, the cell includes a first liquid crystal layer 45 and asecond liquid crystal layer 48. The first liquid crystal layer 45 isdisposed in a gap between an upper (first) liquid crystal polymericlayer 44 and an intermediate (second) liquid crystal polymeric layer 47.The second liquid crystal layer 48 is disposed in a gap between theintermediate liquid crystal polymeric layer 47, and a lower (third)liquid crystal polymeric layer 50.

The upper polymeric layer 44 has directors on the lower surface adjacentthe liquid crystal layer 45 that are parallel to the surface of theliquid crystal layer 45, and orthogonal to the plane of theillustration. The intermediate polymeric layer 47 has directors on theupper surface adjacent to the liquid crystal layer 45 that are parallelto the surface of liquid crystal layer 45, and orthogonal to the planeof the illustration (i.e., parallel to the directors on the lowersurface of the upper polymeric layer 44). The intermediate polymericlayer 47 has directors on the lower surface adjacent to the liquidcrystal layer 48 that are parallel to the surface of the liquid crystallayer 48, and parallel to the plane of the illustration (i.e. orthogonalto the directors on the upper surface of the intermediate polymericlayer 47). Lower polymeric layer 50 has directors on its upper surfaceadjacent to the liquid crystal layer 48 parallel to the surface of theliquid crystal layer 48 and parallel to the plane of the illustration(i.e., parallel to the directors on the lower surface of theintermediate polymeric layer 47).

The polymeric layers 44, 47, 50 act as alignment layers for the liquidcrystal layers. The intermediate polymeric layer 47 has orthogonaldirectors on its upper and lower surfaces. The upper and lower polymericlayers 44, 50 may be replaced in some embodiments by other alignmentlayer materials, such as a brushed polyimide layer. Utilizing brushedpolyimide in the intermediate polymeric layer may not be practical,because of optical losses and other problems. Thus, the alignmenttechnique between the liquid crystal layers in preferred embodimentsinvolves the use of a liquid crystal polymeric layer with orthogonaldirectors on its upper and lower surfaces.

The liquid crystal layers 45 and 48 comprise liquid crystal materialconfined in the gap, and have identical thicknesses between thepolymeric layers, within reasonable manufacturing and opticalperformance tolerances.

An array of posts (e.g. 46) is disposed in a gap between the upperpolymeric layer 44 and the intermediate polymeric layer 47, and issurrounded by the liquid crystal material in the liquid crystal layer45. The posts in the array extend from the upper polymeric layer 44 tothe intermediate polymeric layer 47, tending to maintain the thicknessas discussed above.

A second array of posts (e.g. 49) is disposed in a gap between theintermediate polymeric layer 47 and the lower polymeric layer 50. Thesecond array of posts is surrounded by the liquid crystal material inthe liquid crystal layer 48 confined in the gap.

In this example, electrical components are disposed in a dielectricpolymer substrate, including layers 40, 43, 52. Electrical componentsinclude a resistive layer 41, a patterned electrode layer 42 disposedover the upper polymeric layer 44, and a transparent pad electrode layer51 below the lower polymeric layer 50.

The liquid crystal cell of FIG. 3A can maintain its optical propertiesafter having been folded over a small radius, and returned to theoriginal shape.

In general, the two-layer liquid crystal cell can provide a positivelens power for unpolarized light, when an electric field is appliedthrough patterned electrodes. The added lens power by the liquid crystallayers is tunable by changing the amplitude, frequency or both of theapplied electric field.

FIGS. 3B through 3D illustrate alternative configurations of two-layerliquid crystal cells like that of FIG. 3A. The same reference numeralsare utilized to refer to like components, which are not described againin some instances. The liquid crystal cells of FIGS. 3B-3D can likewisemaintain their optical properties after having been folded over a smallradius, and returned to the original shape.

As shown in FIG. 3B, in alternative configurations, a polyimide layercan be used with the resistive layer to improve its uniformity. Thus, inFIG. 3B the two-layer liquid crystal cell is modified by adding apolyimide layer 60 in contact with the resistive layer 41.

In FIG. 3C, an embodiment is illustrated in which the two-layer liquidcrystal cell is modified by the addition of the polyimide layer 60 incontact with the resistive layer 41, and by moving the upper patternedelectrode layer 42 into contact with the upper surface of the upperpolymeric layer 44, thereby eliminating the region of layer 43 of thedielectric substrate that is shown in FIGS. 3A and 3B. This has theeffect of decreasing the required operating voltage and total thicknessof the flexible liquid crystal cell.

In FIG. 3D, an embodiment is illustrated in which the two-layer liquidcrystal cell is modified relative to the structure of FIG. 3A, by movingthe resistive layer 41 into contact with the upper surface of the upperpolymeric layer 44, eliminating much of the region of layer 43 of thedielectric substrate, and eliminating the polyimide layer of FIG. 3B andFIG. 3C. This further reduces the overall thickness of the structure,and eliminates the requirement for the polyimide layer.

An embodiment of a method for manufacturing flexible liquid crystal celllike that of FIG. 2 is illustrated in FIGS. 4(a) to FIG. 4(f).

FIG. 4(a) illustrates an empty process cell as a first illustrated stagein the process. The empty process cell consists of upper and lower glasslayers 80, 82 which act as cover layers during the forming of the cell.The glass layers are coated with the substrate dielectric material 70,72, 79, the electrode material 71, 78, the resistive layer 73, and thealignment layers 74, 77, which in this example are polymeric layers asdiscussed above. The upper electrode material 71 is patterned to definea hole used to induce a variable electric field as discussed above toprovide for a tunable lens power. The lower electrode material 78 isdisposed in a pad shape. A Mylar film spacer 75 is disposed between theupper polymeric layer 74 and the lower polymeric layer 77 to define agap 76 in which the liquid crystal layer and the array of posts is to beformed. In this example, the Mylar film spacer 75 defines a gapthickness of 35 μm.

As shown in FIG. 4(b), in a next stage of the manufacturing acombination of the liquid crystal material and polymer precursors isinjected into the gap 76, relying on capillary force for example. Insome embodiments, the combination includes liquid crystalline monomermoieties 100, a photo-initiator 101, and liquid crystal moieties 102.More specifically in one example process, a combination consists ofnematic LC (LCM-1656), liquid crystalline monomer (RM257), and aphoto-initiator (IRG184) at ratio of 99 wt %:0.5 wt %:0.5 wt %. LCM-1656can be obtained from LC Matter Corp., (e.g., Orlando, FL, USA;lcmatter.com), RM-257 and IRG-184 can be obtained from Merck or MerckKgaA (Darmstadt, Germany, merckgroup.com). The materials chosenpreferably result in formation of polymer posts having sufficientstiffness to resist severe deformation, but having good elasticity inorder to restore the cell gap in the structure after bending.

FIG. 4(c) illustrates a next stage in the manufacturing process. Thecell, with the combination material injected into the gap 76, is alignedwith the lithographic mask 110 that defines an array of holes 112, 113.The structure is then exposed to actinic radiation 111, such as UVradiation in the present example. During the exposure, in a phaseseparation process the liquid crystal moieties 125 drift away from theregions exposed to the ultraviolet light through the holes 112, 113,while the liquid crystal monomers 120, 121 drift into the region ofexposure.

As illustrated in FIG. 4(d), during the exposure 111, polymer chains 135form by photo-polymerization among the liquid crystal monomers 120, 121to form an array of posts extending between the polymeric layers 74, 77.

The exposure 111 can be carried out at low temperature, below 100° C.and, in the example being described, near room temperature (about 20-25°C.). This low temperature photo-polymerization allows manufacturingwithout damage to the layers of the structure that are supported by theglass covers during the photo-polymerization process.

In the next stage, as shown in FIG. 4(e), the cell is removed from thelithographic system, with elastic polymer posts extending from an uppersurface of the lower polymeric layer 77 to the lower surface of theupper polymeric layer 74, and with liquid crystal filling the gap andsurrounding the posts.

FIG. 4(f) illustrates a following stage, in which the glass layers(covers) 80, 82 are removed, leaving the flexible, tunable liquidcrystal cell, such as that shown in FIG. 2 .

The liquid crystal cell is sealed by the Mylar spacers in this exampleusing a UV curable polymer. In this example, the posts are formed in amixture of liquid crystal and monomers during curing by thephoto-polymerization. In another embodiment, the posts may be formed ina first step, followed by removal of uncured material leaving a networkof posts, and then by injection of liquid crystal after the removalaround the network of posts. In some examples, the liquid crystal cellcan be sealed during the curing by using the patterned mask to define asealing region, and closing the cell by the same material as used tomake the posts.

This manufacturing process is extendable to the two-layer cell, such asshown in FIGS. 3A-3D, by adding the intermediate polymeric layer, and asecond Mylar spacer to define the second gap. Otherwise, similarprocessing steps are applied for the two-layer cell.

FIG. 5 illustrates a representative layout for the lithographic mask110, which can be used in the stage of the process described withreference to FIG. 4(c) and FIG. 4(d). In this example, the mask layoutcomprises an array of circular holes 250, 251 having a diameter of about50 μm, and a pitch of about 500 μm in both the horizontal and verticaldimensions. This layout was selected for a liquid crystal layer about 35μm thick, using the materials discussed above. Other layouts can bechosen according to the needs of a particular embodiment. The density ofthe holes translates into a density of posts that are disposed in thegap between the polymeric layers. The density should be selected so asnot to interfere significantly with the electro-optic performance of thecell, while maintaining sufficient elasticity in the sense discussedabove so that the shape of the cell returns to its original shape, afterhaving been deformed by folding.

The holes need not be circular as illustrated in FIG. 5 , but can beelliptical, rectangular, or other more complex shapes. The preferredshape and density of shapes can be determined using empirical methods orsimulation.

FIGS. 6(a) to 6(f) illustrate stages of an embodiment of a method formanufacturing the polymeric layers, which are used as alignment layersin the embodiments discussed above. FIG. 6(a) illustrates a stage of theprocess including an empty process cell consisting of glass layers 800,801 coated with respective layers 802, 806 of a conductor such as ITO,and alignment layers 803, 805, such as brushed polyimide, which havebeen configured to align the directors of the liquid crystal material inthe polymeric layer on the opposing surfaces of the polymeric layeraccording to orientations required for the examples described above. AMylar spacer 804 maintains a gap 810 between the glass layers 800, 801with a thickness that can be adjusted depending on the design. Forexample, the thicknesses of the upper and lower polymeric layers 24, 27in FIG. 2 are about 7 μm, and the thickness of the polymeric layer 47 inFIGS. 3A-3D is about 35 um.

As illustrated in FIG. 6(b), a mixture of a liquid crystal materialincluding liquid crystal moieties 852, a monomer 851 and aphoto-initiator 850 is injected into the empty process cell at atemperature of about 90° C. As a result of the alignment layers 803,806, the monomer, which can be a mesomer having liquid crystalproperties, and liquid crystal are aligned in the mixture according tothe direction set by the alignment layers 803, 805. In this example, thedirectors in this liquid phase are aligned in the plane of theillustration, and parallel with the plane of the alignment layers 803,805.

As shown in FIG. 6(c), the conductive ITO layers 802, 806 are connectedto a power supply at 900 which applies a high AC voltage whichre-orients the molecules of both the monomer (e.g. 856) and the liquidcrystal moieties (857) parallel to the z-axis 5 orthogonal to thesurfaces of the glass covers. However, due to the strong anchoring forceprovided by the alignment layers, the molecular orientations (e.g. 854,855) near the alignment layer surfaces remain parallel to the rubbingdirections.

As illustrated in FIG. 6(d), the structure is exposed to actinic UVradiation 910 while the AC electric field is applied. This radiationtriggers the photo-initiator and activates the photo-polymerization ofthe monomer. When the monomer reacts to form polymer chains, thepolymeric films with embedded liquid crystal moieties results betweenthe two glass covers. A polymer network (e.g. 860) that results from thepolymerization traps and helps to maintain the orientation of the liquidcrystal molecules in the polymeric layer.

As illustrated in FIG. 6(e), after the polymerization is complete, theelectric field and UV radiation can be removed. Then, as shown in FIG.6(f), the glass covers 800, 801, along with the ITO and alignment layers(802, 803 and 805, 806) are peeled off of the polymeric layer 1000.

As a result, the polymeric layer in this example can be opticallyanisotropic since the directors of the liquid crystal moieties throughthe majority of the polymeric layer in the center away from the surfacesin contact with the alignment layers lie on the z-axis. The liquidcrystal molecules on the surface of the polymeric layers remain disposedparallel to the surfaces of the alignment layer and confined by thepolymer networks. Thus the surface of the polymeric layer can be used toalign liquid crystal molecules in the liquid crystal layer in thestructures described above.

This process can be used to set different orientations of the liquidcrystal molecules on the surface of the polymeric layers, by changingthe rubbing directions and materials of the alignment layers 803, 805during fabrication. Also, by applying variable electric fields duringpolymerization, the alignment direction throughout the polymeric layercan be caused to tilt, resulting in a passive lens effect.

In one specific example, the polymeric layer consists of reactivemesogen (RM257), liquid crystal (MLC2144) and the photo-initiator(IRG184) with the ratio of RM257:MLC2144: IRG184=79 wt %:20 wt %: 1 wt%. RM257 is1,4-Bis[4-(3-acryloyloxypropyloxy)benzoyloxy]-2-methylbenzene with theCAS 174063-87-7. IRG184 is 1-Hydroxycyclohexyl phenyl ketone with theCAS 947-19-3.

In one embodiment, the reactive monomer used for the purposes of formingthe posts as discussed with reference to FIGS. 4(a) to 4(f) can be thesame (e.g. RM257) as used as a reactive monomer in the formation of thepolymeric layers. In other embodiments, the polymer precursors can bedifferent in the two procedures. Also, different polymer precursors andliquid crystal materials can be used for different polymeric layers insome embodiments.

The materials for fabricating polymeric layers are not limited to RM257,IRG184 and MLC2144. Alternative materials can include other liquidcrystalline monomers and photo-initiators. Also, the liquid crystal(MLC2144) could be replaced by other nematic liquid crystals.

FIG. 7 illustrates a flexible single-layer liquid crystal cell formed ona curved substrate. This structure can be made using the processdescribed above, for example, with glass covers in the process cellhaving curved surfaces. The liquid crystal cell includes a liquidcrystal layer 325 disposed in a gap between polymeric layer 324 andpolymeric layer 327, where the polymeric layers 324 and 327 compriseflexible or elastic polymer mixed with liquid crystal moietiesconfigured to act as alignment layers for the liquid crystal layer 325.The polymeric layers 324, 327 have liquid crystal moieties having avertical director in the central region of the layers, and horizontaldirectors on the surfaces. In the upper polymeric layer 324 in thisexample, the directors on the surfaces are horizontal relative to themajor surface of the liquid crystal layer 325, and parallel to the planeof the illustration. In the lower polymeric layer 327 in this example,the directors on the upper surface are horizontal relative to the majorsurface of the liquid crystal layer 325, and parallel to the plane ofthe illustration. On the lower surface of the lower polymeric layers327, the directors are parallel to those on the upper surface. Theorientations of the directors in this example result in the alignmentdirections on the upper and lower surfaces of the liquid crystal layer325 parallel to one another.

An array of posts (e.g. post 326) is disposed in the liquid crystallayer 325. The posts in the array extend from the upper polymeric layer324 to the lower polymeric layer 327, and tend to maintain the thicknessof the liquid crystal layer 325.

Preferably the posts and the polymeric layers comprise an elasticpolymer or elastomer.

The liquid crystal is confined in the gap between the first and secondpolymeric layers around the posts in the array of posts.

In this example, electrical components are disposed in a dielectricpolymer (including layers 320, 322, 329 in this example). The electricalcomponents include a resistive layer 323, a patterned electrode layer321 over the upper polymeric layer 324, and pad electrode layer 328below the lower polymeric layer 327.

In one representative embodiment, the substrate of the liquid crystalcell includes the dielectric layers 320, 322 comprising PDMS.

The radius of curvature of the cell can range in various embodimentsfrom about 100 mm to 8 mm or less. For example, the radius of curvaturecan range from 100 mm to 1 mm.

Embodiments of the liquid crystal cell shown in FIG. 7 can maintainoptical properties after having been folded over a small radius, andreturned to the original shape.

FIG. 8 illustrates a flexible two-layer liquid crystal cell formed on acurved substrate. In FIG. 8 , the cell includes a first liquid crystallayer 425 and a second liquid crystal layer 428. The first liquidcrystal layer 425 is disposed in a gap between an upper (first) liquidcrystal polymeric layer 424 and an intermediate (second) liquid crystalpolymeric layer 427. The second liquid crystal layer 428 is disposed ina gap between the intermediate liquid crystal polymeric layer 427, and alower (third) liquid crystal polymeric layer 430.

The upper polymeric layer 424 has directors on the lower surfaceadjacent the liquid crystal layer 425 that are orthogonal to the z-axis5 of the cell, and parallel to the plane of the illustration. Theintermediate polymeric layer 427 has directors on the upper surfaceadjacent to the liquid crystal layer 425 that are orthogonal to thez-axis 5, and parallel to the plane of the illustration (i.e. parallelto the directors on the lower surface of the upper polymeric layer 424).The intermediate polymeric layer 427 has directors on the lower surfaceadjacent to the liquid crystal layer 428 that are orthogonal to thez-axis 5, and orthogonal to the plane of the illustration (i.e.orthogonal to the directors on the upper surface of the intermediatepolymeric layer 427). Lower polymeric layer 430 has directors on itsupper surface adjacent to the liquid crystal layer 428 orthogonal to thez-axis 5 and orthogonal to the plane of the illustration (i.e. parallelto the directors on the lower surface of the intermediate polymericlayer 427).

The polymeric layers 424, 427, 430 act as alignment layers for theliquid crystal layers. The intermediate polymeric layer 427 hasorthogonal directors on its upper and lower surfaces. The upper andlower polymeric layers 424, 430 may be replaced in some embodiments byother alignment layer materials, such as a brushed polyimide layer.

An array of posts (e.g. 426) is disposed in a gap between the upperpolymeric layer 424 and the intermediate polymeric layer 427, and issurrounded by the liquid crystal material in the liquid crystal layer425 confined in the gap. The posts in the array extend from the upperpolymeric layer 424 to the intermediate polymeric layer 427, tending tomaintain the thickness as discussed above.

A second array of posts (e.g. 429) is disposed in a gap between theintermediate polymeric layer 427 and the lower polymeric layer 430. Thesecond array of posts is surrounded by the liquid crystal material inthe liquid crystal layer 428 confined in the gap.

In this example, electrical components are disposed in a dielectricpolymer substrate, including layers 432, 433, 434. Electrical componentsinclude a resistive layer 423, a patterned electrode layer 421 disposedover the upper polymeric layer 424, and a pad electrode layer 431 belowthe lower polymeric layer 430.

The curved embodiments of FIGS. 7 and 8 can provide passive, additivelens power to the electroactive component of the cell.

Embodiments of the liquid crystal cells shown in FIGS. 7 and 8 canmaintain optical properties after having been folded over a smallradius, and returned to the original shape.

FIG. 9 illustrates another embodiment of a two-layer liquid crystal cellutilizing hybrid alignment of the liquid crystal molecules in the liquidcrystal layers. The cell includes a first liquid crystal layer 505 and asecond liquid crystal layer 508. The first liquid crystal layer 505 isdisposed in a gap between an upper vertical alignment layer 504, whichcan comprise PDMS for example, and an intermediate polymeric layer 507.The second liquid crystal layer 508 is disposed in a gap between theintermediate polymeric layer 507, and a lower vertical alignment layer510.

The intermediate polymeric layer 507 has directors on the upper surfaceadjacent to the liquid crystal layer 505 that are orthogonal to thez-axis 5 (parallel to the surface of liquid crystal layer 505), andorthogonal to the plane of the illustration. The intermediate polymericlayer 507 has directors on the lower surface adjacent to the liquidcrystal layer 508 that are orthogonal to the z-axis 5, and parallel tothe plane of the illustration (i.e. orthogonal to the directors on theupper surface of the intermediate polymeric layer 507).

The directors in the liquid crystal layers 505, 508 adjacent to theupper vertical alignment layer 504 and the lower vertical alignmentlayer 510 are arranged vertically, parallel to the z-axis 5, in theplane of the illustration. The directors in the liquid crystal layerstwist between the upper and lower surfaces of liquid crystal layers 505,508 as illustrated, in orthogonal planes because of the alignmentfunction of the intermediate polymeric layer 507.

The liquid crystal layers 505 and 508 have identical thickness betweenthe polymeric layers, within reasonable manufacturing and opticalperformance tolerances.

An array of posts (e.g. 506) is disposed in a gap between the upperalignment layer 504 and the intermediate polymeric layer 507, and issurrounded by the liquid crystal material in the liquid crystal layer505 confined in the gap. The posts in the array extend from the upperalignment layer 504 to the intermediate polymeric layer 507, tending tomaintain the thickness as discussed above.

A second array of posts (e.g. 509) is disposed in a gap between theintermediate polymeric layer 507 and the lower alignment layer 510. Thesecond array of posts is surrounded by the liquid crystal material inthe liquid crystal layer 508 confined in the gap.

In this example, electrical components are disposed in a dielectricpolymer substrate, including layers 512, 510, 500, 504. Electricalcomponents include a resistive layer 502, a polyimide layer 501, apatterned electrode layer 503 disposed over the upper alignment layer504, and a pad electrode layer 511 below the lower alignment layer 510.In this structure, the response time can be faster than that of thestructure described with reference to FIGS. 3A-3D. However, the tunablerange may be lesser.

FIG. 10 illustrates an alternative embodiment like that of FIG. 9 , andthe same reference numbers are used to refer to the same components, andnot described again. In this embodiment, the position of the patternedelectrode 523 and the resistive film 521/polyimide film 522 structuresare reversed, so that the patterned electrode 523 overlies the resistivefilm 521. Otherwise the structures are similar, and can behave insimilar fashions.

The liquid crystal cells of FIG. 9 and FIG. 10 can maintain theiroptical properties after having been folded over a small radius, andreturned to the original shape.

In alternative embodiments, a patterned electrode may not be utilized. Anon-uniform electric field can be generated by a pair of transparentpad-shaped electrodes with the addition of dielectric layers havingspatially distributed dielectric constants or surfaces into thestructure.

FIG. 11 illustrates one embodiment of the structure having transparentelectrodes 601 and 610 without electrode patterning.

The cell shown in FIG. 11 includes a first liquid crystal layer 604 andthe second liquid crystal layer 607. The first liquid crystal layer 604is disposed in a gap between an upper (first) liquid crystal polymericlayer 603 and an intermediate (second) liquid crystal polymeric layer606. The second liquid crystal layer 607 is disposed in a gap betweenthe intermediate liquid crystal polymeric layer 606 and a lower (third)liquid crystal polymeric layer 609.

The upper polymeric layer 603 has directors on the lower surfaceadjacent the liquid crystal layer 604 that are orthogonal to the z-axis5 (parallel to the surface of liquid crystal layer 604) and orthogonalto the plane of the illustration. The intermediate polymeric layer 606has directors on the upper surface adjacent to the liquid crystal layer604 that are orthogonal to the z-axis 5 (parallel to the surface ofliquid crystal layer 604), and orthogonal to the plane of theillustration (i.e. parallel to the directors on the lower surface of theupper polymeric layer 603). The intermediate polymeric layer 606 hasdirectors on the lower surface adjacent to the liquid crystal layer 607that are orthogonal to the z-axis 5 (parallel to the surface of liquidcrystal layer 607), and parallel to the plane of the illustration (i.e.orthogonal to the directors on the upper surface of the intermediatepolymeric layer 606). Lower polymeric layer 609 has directors on itsupper surface adjacent to the liquid crystal layer 607 that areorthogonal to the z-axis 5 (parallel to the surface of liquid crystallayer 607) and parallel to the plane of the illustration (i.e. parallelto the directors on the lower surface of the intermediate polymericlayer 606).

The liquid crystal layers 604 and 607 have identical thickness betweenthe polymeric layers, within reasonable manufacturing and opticalperformance tolerances.

An array of posts (e.g. 605) is disposed in a gap between the upperpolymeric layer 603 and the intermediate polymeric layer 606, and issurrounded by the liquid crystal material in the liquid crystal layer604 confined in the gap. The posts in the array extend from the upperpolymeric layer 603 to the intermediate polymeric layer 606, tending tomaintain the thickness as discussed above.

A second array of posts (e.g. 608) is disposed in a gap between theintermediate polymeric layer 606 and the lower polymeric layer 609. Thesecond array of posts is surrounded by the liquid crystal material inthe liquid crystal layer 607 confined in the gap.

In this example, electrical components are disposed in a dielectricpolymer substrate, including layers 600, 602, 611. Electrical componentsinclude flat transparent electrodes 601 disposed over the upperpolymeric layer 603, and flat transparent electrodes 610 below the lowerpolymeric layer 609.

In this kind of structure, there is no need for a resistive layer or apatterned electrode. However, the overall thickness of the structure canbe increased. The polymeric layers 603, 606, 609 act as alignment layersfor the liquid crystal layers. The intermediate polymeric layer 606 hasorthogonal directors on its upper and lower surfaces. In this example,the upper surface 603A of the upper polymeric layer 603 is curved, alongwith a matching curve of the dielectric material in layer 602. The curvecan result in generation of a non-uniform electric field when a voltageis applied on the flat transparent electrodes 601 and 610.

The liquid crystal cell of FIG. 11 can maintain its optical propertiesafter having been folded over a small radius, and returned to theoriginal shape.

FIG. 12 illustrates another embodiment in which flat transparentelectrodes are used rather than patterned electrodes. In FIG. 12 , atwo-layer liquid crystal cell utilizing hybrid alignment of the liquidcrystal molecules in the liquid crystal layers is illustrated. The cellin FIG. 12 includes a first liquid crystal layer 704 and a second liquidcrystal layer 707. The first liquid crystal layer 704 is disposed in agap between an upper vertical alignment layer 703, which can comprisePDMS for example, and an intermediate polymeric layer 706. The secondliquid crystal layer is disposed in a gap between the intermediatepolymeric layer 706, and a lower vertical alignment layer 709.

The intermediate polymeric layer 706 has directors on the upper surfaceadjacent to the liquid crystal layer 704 that are orthogonal to thez-axis 5 (parallel to the surface of liquid crystal layer 704), andorthogonal to the plane of the illustration. The intermediate polymericlayer 706 has directors on the lower surface adjacent to the liquidcrystal layer 707 that are orthogonal to the z-axis 5 (parallel to thesurface of liquid crystal layer 707), and lie in the plane of theillustration (i.e. orthogonal to the directors on the upper surface ofthe intermediate polymeric layer 706). A curved polymeric layer 702 isdisposed over and in contact with the upper alignment layer 703. Thisforms a curved surface 703A in the path of the electric field betweenthe flat transparent electrodes 701 and 710.

The PDMS layers act as vertical alignment layers 703, 709 for thestructure. As a result, the directors in the liquid crystal layers 704,707 adjacent to the upper vertical alignment layer 703 and the lowervertical alignment layer 709 are arranged vertically, along the opticalpath. The directors in the liquid crystal layers twist in orthogonalplanes between the upper and lower surfaces as illustrated, because ofthe alignment function of the intermediate polymeric layer 706.

The liquid crystal layers 704 and 707 have identical thickness betweenthe polymeric layers, within reasonable manufacturing and opticalperformance tolerances.

An array of posts (e.g. 705) is disposed in a gap between the upperalignment layer 703 and the intermediate polymeric layer 706, and issurrounded by the liquid crystal material in the liquid crystal layer704 confined in the gap. The posts in the array extend from the upperalignment layer 703 to the intermediate polymeric layer 706, tending tomaintain the thickness as discussed above.

A second array of posts (e.g. 708) is disposed in a gap between theintermediate polymeric layer 706 and the lower alignment layer 709. Thesecond array of posts is surrounded by the liquid crystal material inthe liquid crystal layer 707 confined in the gap.

In this example, electrical components include a flat transparentelectrode layer 701 disposed over the curved polymeric layer 702, and aflat transparent electrode layer 710 below the lower alignment layer709. Dielectric substrate layers 700, 711 are disposed on the opposingsurfaces of the cell.

The liquid crystal cell of FIG. 12 can maintain its optical propertiesafter having been folded over a small radius, and returned to theoriginal shape.

As mentioned above, the orientation of the liquid crystal molecules inthe liquid crystal and polymer films can be defined by an externalelectric field applied during the photo-polymerization. By applying anon-uniform electric field during the process, the resulting liquidcrystal polymer film can have a fixed lens power. Using the lens powerof liquid crystal polymer lenses in combination with the flexibleelectroactive components can add lens power to the structure.

An example two-layer liquid crystal electroactive cell, with lens poweradded by the liquid crystal polymeric layers is shown in FIG. 13 .

In FIG. 13 , the cell includes a first liquid crystal layer 954 and asecond liquid crystal layer 957. The first liquid crystal layer 954 isdisposed in a gap between an upper (first) liquid crystal polymericlayer 953 and an intermediate (second) liquid crystal polymeric layer956. The second liquid crystal layer 957 is disposed in a gap betweenthe intermediate liquid crystal polymeric layer 956, and a lower (third)liquid crystal polymeric layer 959.

The upper polymeric layer 953 has directors between its surfacesdistributed to induce lens power, and has directors on its upper andlower surfaces that are orthogonal to the z-axis 5 (parallel to thesurface of liquid crystal layer 954), and orthogonal to the plane of theillustration. The directors between the surfaces of the upper polymericlayer 953 tilt by amounts that are a function of their location relativeto center line of the optical zone, in planes parallel to the z-axis 5,and orthogonal to the plane of the illustration in this example.

The intermediate polymeric layer 956 has directors on the upper surfaceadjacent to the liquid crystal layer 954 that are orthogonal to thez-axis 5 (parallel to the surface of liquid crystal layer 954), andorthogonal to the plane of the illustration (i.e. parallel to thedirectors on the lower surface of the upper polymeric layer 953). Theintermediate polymeric layer 956 has directors on the lower surfaceadjacent to the liquid crystal layer 957 that are orthogonal to thez-axis 5 (parallel to the surface of liquid crystal layer 957), andparallel to the plane of the illustration (i.e. orthogonal to thedirectors on the upper surface of the intermediate polymeric layer 956).The directors between the surfaces and the intermediate polymeric layer956 are arranged vertically.

Lower polymeric layer 959 has directors between its surfaces distributedto induce lens power, and has directors on its upper and lower surfacesthat are orthogonal to the z-axis 5 (parallel to the surface of liquidcrystal layer 957) and parallel to the plane of the illustration (i.e.parallel to the directors on the lower surface of the intermediatepolymeric layer 956). The directors between the surfaces of the lowerpolymeric layer 959 tilt by amounts that are a function of theirlocation relative to center line of the optical zone, in planes parallelto the z-axis 5, and parallel to the plane of the illustration in thisexample. As a result, the orientations of the directors between thesurfaces in the upper and lower polymeric layers are orthogonal to oneanother.

The polymeric layers 953, 956, 959 act as alignment layers for theliquid crystal layers.

The liquid crystal layers 954 and 957 have identical thickness betweenthe polymeric layers, within reasonable manufacturing and opticalperformance tolerances.

An array of posts (e.g. 955) is disposed in a gap between the upperpolymeric layer 953 and the intermediate polymeric layer 956, and issurrounded by the liquid crystal material in the liquid crystal layer954 confined in the gap. The posts in the array extend from the upperpolymeric layer 953 to the intermediate polymeric layer 956, and tend tomaintain the thickness as discussed above.

A second array of posts (e.g. 958) is disposed in a gap between theintermediate polymeric layer 956 and the lower polymeric layer 959. Thesecond array of posts is surrounded by the liquid crystal material inthe liquid crystal layer 957 confined in the gap.

In this example, electrical components are disposed in a dielectricpolymer substrate, including layers 950, 961, 962. Electrical componentsinclude a resistive layer 951B, with the contacting polyimide layer951A, a patterned electrode layer 952 disposed over the upper polymericlayer 953, and a transparent pad electrode layer 960 below the lowerpolymeric layer 959.

The distributed directors in the upper polymeric layer 953 and the lowerpolymeric layer 959 provide added lens power to the electroactive cell.In some embodiments, the passive lens power provided by the polymericlayers 953 and 959 can be combined with electroactive power provided bythe liquid crystal layers to enable utilization of the lens structure tofocus on near objects and on far objects.

The liquid crystal cell of FIG. 13 can maintain its optical propertiesafter having been folded over a small radius, and returned to theoriginal shape.

The flexible liquid crystal cell technology described is suitable foruse in flexible lenses, such as contact lenses, which can be elastic inthe sense that the structure will return to its original shape andoriginal optical properties after having been folded.

Embodiments of flexible liquid crystal cells can include optics that areall polymer based. In some embodiments, the liquid crystal cell caninclude a polarizer or be polarizer-free. In some embodiments, there isa single liquid crystal layer. In other embodiments there are two ormore liquid crystal layers.

The technology described for manufacturing an array of posts within aliquid crystal layer is based on photo-polymerization at low temperatureof a mixture including polymer precursors and liquid crystal material.The photo-polymerization induces a phase separation and polymerizationof the precursors to form the array of posts, according to a patternformed using a lithographic mask for example.

Flexible liquid crystal cells described herein can be folded onthemselves without breaking, and can be returned to the original shapewhile recovering optical properties of the electroactive lens.

For example, the thickness of the liquid crystal layers can bemaintained before and after folding, such that the average thicknessbefore and after folding remains within 10% of the initial thickness.Also, the thickness of the liquid crystal layers can be a uniformthickness before and after folding, varying for example by less than 1.2μm from the center of the optic to the edge of the effective aperture ofthe optic.

The technology is described for implementing flexible optical elementsthat use liquid crystals to realize electrically tunable optics. Theliquid crystal optics can include a pair of liquid crystal layers withorthogonally aligned liquid crystal directors to enable polarizer-freeoperation, with flexible polymeric alignment layers, flexible substratesand a module for controlling the electric field. Lens power of theliquid crystal optics can be changed by controlling the distribution ofthe electric field across the entire optical zone. For patients withmyopia and presbyopia, a flexible contact lens can be implemented usingthe technology described herein with a negative lens power for thepurposes of focusing on far objects, and an additive lens power for thepurposes focusing on near objects. In some examples, the negative lenspower can be provided by passive structure of the stack of opticallayers, combined with the electro-optic active structure of the liquidcrystal layers. Thus, it can be understood that a flexible contact lenscan include a flexible optical element that uses liquid crystals, asdescribed herein.

A flexible optical element adopting liquid crystals (LCs) as thematerials for realizing electrically tunable optics is described. The LCoptics can include a pair of LC layers with orthogonally aligned LCdirectors for polarizer-free operation, flexible polymeric alignmentlayers, flexible substrates, and a module for controlling the electricfield. The lens power of the LC optics can be changed by controlling thedistribution of electric field across the optical zone. The liquidcrystal cells as described herein can be included in a contact lens thatcomprises a flexible polymer.

For patients with myopia and presbyopia, or hyperopia and presbyopia,simultaneously, a flexible contact lens is described with negative lenspower to support focus on far objects and an added positive lens powerto support focus on near objects. The LC optics can provide the addedpositive lens power electrically and can be combined with the flexiblecontact lens with passive, initial negative lens power for thosepatients.

Manufacturing processes described herein have been described in aparticular order. Some of the steps can be combined, performed inparallel or performed in a different sequence without affecting thefunctions achieved. In some cases, as the reader will appreciate, arearrangement of steps will achieve the same results only if certainother changes are made as well. In other cases, as the reader willappreciate, a re-arrangement of steps will achieve the same results onlyif certain conditions are satisfied.

While the present invention is disclosed by reference to the preferredembodiments and examples detailed above, it is to be understood thatthese examples are intended in an illustrative rather than in a limitingsense. It is contemplated that modifications and combinations willreadily occur to those skilled in the art, which modifications andcombinations will be within the spirit of the invention and the scope ofthe following claims.

What is claimed is:
 1. A flexible electrically tunable liquid crystallens, comprising: a liquid crystal cell having a cell gap thickness Xprior to bending the liquid crystal lens, and a cell gap thickness Yafter returning to shape after the bending of the liquid crystal lens,wherein Y=X±10% X, wherein the liquid crystal cell comprises elasticposts effective in limiting changes in the cell gap thickness tomaintain Y=X±10%, wherein the liquid crystal cell includes first andsecond alignment layers and a layer of liquid crystal between the firstand second alignment layers, and wherein the first and second alignmentlayers comprise a flexible polymeric material, and wherein at least oneof the first and second alignment layers has liquid crystal moietieswith distributed directors which induce passive lens power.
 2. Theflexible electrically tunable liquid crystal lens of claim 1, whereinthe liquid crystal cell comprises elastic polymer posts effective inlimiting changes in the cell gap thickness to maintain Y=X±10% X.
 3. Theflexible electrically tunable liquid crystal lens of claim 1, includinga polymer lens body encasing the liquid crystal cell.
 4. The flexibleelectrically tunable liquid crystal lens of claim 1, wherein the elasticposts form an array of polymer posts extending through the layer ofliquid crystal, and are bonded to the first and second alignment layers.5. The flexible electrically tunable liquid crystal lens of claim 1,wherein said bending includes folding the cell on a radius of 1 to 9 mm.6. The flexible electrically tunable liquid crystal lens of claim 1,wherein the liquid crystal cell includes: first, second and thirdalignment layers; a first layer of liquid crystal between the first andsecond alignment layers; and a second layer of liquid crystal betweenthe second and third alignment layers, wherein the second alignmentlayer includes a combination of liquid crystal and polymer material. 7.The flexible electrically tunable liquid crystal lens of claim 6,wherein at least one of the first and third alignment layers has liquidcrystal moieties with distributed directors which induce passive lenspower.
 8. The flexible electrically tunable liquid crystal lens of claim1, wherein the liquid crystal cell includes: a first alignment layer anda second alignment layer with a gap between them; an array of elasticpolymer posts in the gap between the first alignment layer and thesecond alignment layer; liquid crystal confined in the gap between thefirst and second alignment layers around the array of elastic polymerposts; and one or more electrodes arranged to induce an electric fieldin the liquid crystal to control lens power of the lens.
 9. The flexibleelectrically tunable liquid crystal lens of claim 1, wherein at least aportion of the distributed directors are orthogonal to an optical path.10. The flexible electrically tunable liquid crystal lens of claim 1,further comprising: first and second alignment layers, wherein theliquid crystal cell is between the first and second alignment layers,and wherein the cell gap thickness of the liquid crystal cell ismeasured as the thickness of the liquid crystal cell as located betweenthe first and second alignment layers.
 11. The flexible electricallytunable liquid crystal lens of claim 1, wherein the elastic posts areformed within the cell through photo-polymerization of a polymerprecursor according to a pattern.
 12. The flexible electrically tunableliquid crystal lens of claim 11, wherein the elastic posts are elasticpolymer posts.